Polymer, resist composition and patterning process

Abstract

A polymer comprising recurring units of formula (1-1) or (1-2) wherein R 1 and R 2 are H or C 1-15 alkyl, R 1 and R 2 , taken together, may form a ring; R 3 is H, C 1-15 alkyl, acyl or alkylsulfonyl or C 2-15 alkoxycarbonyl or alkoxyalkyl which may have halogen substituents, not all R 1 , R 2 and R 3 are hydrogen; and k=0 or 1, and having a Mw of 1,000-500,000 is novel. A resist composition comprising the polymer as a base resin is sensitive to high-energy radiation, has excellent sensitivity, resolution, etching resistance, and minimized swell and lends itself to micropatterning with electron beams or deep-UV.

What is claimed is:  
     
       1. A polymer comprising recurring units of the following general formula (1-1) or (1-2) and having a weight average molecular weight of 1,000 to 500,000,                    
       wherein R 1  and R 2  each are hydrogen or a straight, branched or cyclic alkyl group of 1 to 15 carbon atoms, R 1  and R 2   1 , taken together, may form a ring, wherein the combination of R 1  with R 2  is a straight, branched or cyclic alkylene group of 2 to 15 carbon atoms,  
       R 3  is hydrogen, a straight, branched or cyclic alkyl, acyl or alkylsulfonyl group of 1 to 15 carbon atoms or a straight, branched or cyclic alkoxycarbonyl or alkoxyalkyl group of 2 to 15 carbon atoms, in which some or all of the hydrogen atoms on constituent carbon atoms may be substituted with halogen atoms, with the case that all R 1 , R 2  and R 3  are hydrogen being excluded, and  
       k is 0 or 1.  
     
     
       2. The polymer of  claim 1  comprising, in addition to the recurring units of formula (1-1), recurring units of the following general formula (2-1):                    
       wherein  
       R 4  is hydrogen, methyl or CH 2 CO 2 R 6 ,  
       R 5  is hydrogen, methyl or CO 2 R 6 ,  
       R 6  is a straight, branched or cyclic alkyl group of 1 to 15 carbon atoms,  
       R 7  is an acid labile group,  
       R 8  is selected from the class consisting of a halogen atom, a hydroxyl group, a straight, branched or cyclic alkoxy, acyloxy or alkylsulfonyloxy group of 1 to 15 carbon atoms, and a straight, branched or cyclic alkoxycarbonyloxy or alkoxyalkoxy group of 2 to 15 carbon atoms, in which some or all of the hydrogen atoms on constituent carbon atoms may be substituted with halogen atoms,  
       Z is a single bond or a straight, branched or cyclic (p+2)-valent hydrocarbon group of 1 to 5 carbon atoms in which at least one methylene may be substituted with oxygen to form a chain-like or cyclic ether or two hydrogen atoms on a common carbon may be substituted with oxygen to form a ketone,  
       k is 0 or 1, and p is 0, 1 or 2.  
     
     
       3. The polymer of  claim 1  comprising, in addition to the recurring units of formula (1-1), recurring units of the following general formulae (2-1) and (3):                    
       wherein k, p and R 4  to R 8  are as defined above, Y is —O— or —(NR 9 )—, and R 9  is hydrogen or a straight, branched or cyclic alkyl group of 1 to 15 carbon atoms.  
     
     
       4. The polymer of  claim 1  comprising, in addition to the recurring units of formula (1-1), recurring units of the following general formula (4) alone or in combination with recurring units of the following general formula (2-1), and recurring units of the following general formula (3):                    
       wherein k, p, R 4  to R 8  and Y are as defined above.  
     
     
       5. The polymer of  claim 1  comprising, in addition to the recurring units of formula (1-2), recurring units of the following general formula (2-2):                    
       wherein k, p and R 4  to R 8  are as defined above.  
     
     
       6. A resist composition comprising the polymer of  claim 1 . 
     
     
       7. A process for forming a resist pattern comprising the steps of: 
       applying the resist composition of  claim 6  onto a substrate to form a coating,  
       heat treating the coating and then exposing it to high-energy radiation or electron beams through a photo mask, and  
       optionally heat treating the exposed coating and developing it with a developer.